In order to increase work efficiency, contemporary work vehicles such as tractors and wheel loaders, for example, Patent document 1 discloses a configuration that is configured so that the revolution power of an engine is transferred to drive wheels via a hydrostatic stepless transmission (HST) and a gear-type sub-transmission (switching between low speed, high speed, and reverse drive) and comprises a throttle lever for setting and holding the output revolution speed of the engine and a speed change pedal for changing the output revolution speed of the hydrostatic stepless transmission, in which when the speed change pedal is stepped on, the accelerator operation section is pushed by the speed change pedal and the output revolution speed of the engine that was set and held by the throttle lever can be increased.
Furthermore, in order to enable the application to a work region in which the range (during forward drive) of the travel speed is comparatively narrow, from several km/h to ten-odd km/h, as in a work vehicle such as tractor or wheel loader, Patent document 2 discloses employing the so-called inline-type stepless transmission instead of the hydrostatic stepless transmission. In the inline-type stepless transmission, an input shaft for transferring the power from an engine and an output shaft for transferring the hydraulic transmission output to the left and right wheels are disposed concentrically, a hydraulic pump unit and a hydraulic motor unit are disposed on both sides of the cylinder block constituting the stepless transmission, and the input shaft and output shaft have a double-shaft configuration. With the inline-type stepless transmission, the power transmission efficiency is good, without leakage of work oil, and fuel consumption of the engine is low.
Patent document 1: JP-A-2003-226165
Patent document 2: JP-A-2002-89655